Reduction of carbon monoxide in mainstream cigarette smoke

ABSTRACT

A smoking article filter is designed to reduce the amount of carbon dioxide (CO) and increase the ratio of total particulate material (TPM) to CO in mainstream cigarette smoke. The design includes a non-porous microcapillary tube centered axially within a low-density filter.

BACKGROUND OF THE DISCLOSURE

a. Field of the Disclosure

The present disclosure relates to a system, a method, and a device configured to reduce carbon monoxide (CO) in mainstream cigarette smoke, as well as for increasing the ratio of total particulate matter (TPM) to CO delivered by a smoking article.

b. Background Art

In 2005, the European Commission established maximal values for “tar”¹ (10 mg), nicotine (1 mg), and carbon monoxide² (CO; 10 mg) per cigarette or “10-1-10,” as measured by the International Organization for Standardization (ISO) method from 1 Jan. 2004. This requirement creates a target tar/CO ratio of 1.0 for commercial smoking products. This is part of a trend of lowering product yield for all smoke compounds delivered in the cigarette, which entails developing new cigarette designs to lower yields while maintaining product taste and acceptability. A common approach to reach these goals is to increase filter ventilation in filtered cigarettes. Other approaches entail the use of adsorbent materials in the filter to adsorb CO and other non-desirable smoke components. However, these technologies tend to impact taste and product acceptability, so alternative technologies to allow control of the tar/CO ratio can be beneficial to the smoking industry. ¹ As used herein, the term “tar” means total particulate matter (TPM) of the mainstream smoke produced from a smoking article after subtracting water and nicotine. The terms will be used interchangeably hereinafter.² Carbon monoxide is a gas inhaled during smoking It has been linked to increased rates of cardiovascular disease.

Prior art FIG. 1A depicts the standard filter design of a traditional filtered cigarette 10A. Traditional filtered cigarettes 10A include a tobacco column 12, including a proximal end 12A and an ignitable distal end 12B, and a filter segment 14A. The mouth end 15 of the cigarette 10A is the proximal end of the filter segment 14A. The tobacco column 12 generates products of combustion that include tar and CO, among other smoke compounds. The filter segment 14A is formed either with a cellulose acetate monorod filter or with cellulose acetate segments that include adsorbent materials. Because traditional filtered cigarettes 10A are normally made using air dilution technology (represented in FIG. 1A by an air ventilation hole 16), CO and tar from the tobacco column 12 are diluted in equal proportion to the percentage of air dilution. Consequently, the standard filter design of traditional filtered cigarettes 10A provides little or no impact on the tar/CO ratio.

BRIEF SUMMARY OF THE DISCLOSURE

According to an aspect of the disclosure, a smoking article filter is designed to reduce the amount of CO and increase the TPM/CO ratio in mainstream cigarette smoke. The design includes a non-porous microcapillary tube centered axially within a low-density filter.

In an embodiment, a smoking article comprises a tobacco column comprising a proximal end and a distal ignitable end, the tobacco column configured to generate products of combustion comprising at least one of tar and carbon monoxide; and a filter segment, comprising a proximal mouth end and a distal end coupled to the tobacco column, the filter segment further comprising a tubular filter structure surrounding a non-porous microcapillary tube, the microcapillary tube centered axially within the tubular filter structure; wherein smoke inhaled by a user at the proximal mouth end of the filter segment comprises a ratio of tar to carbon monoxide that is greater than or equal to 1.0.

In another embodiment, a filter segment for use in a smoking article comprises a tubular filter structure surrounding a non-porous microcapillary tube, the microcapillary tube centered axially within the tubular filter structure; wherein smoke inhaled by a user of the smoking article comprises a ratio of tar to carbon monoxide that is greater than or equal to 1.0.

In another embodiment, a method for reducing an amount of carbon monoxide in mainstream cigarette smoke, the method comprises: inserting a non-porous microcapillary tube axially into a filter segment of a cigarette; and controlling at least one of a diameter of the microcapillary tube, a density of the filter segment, and a degree of air ventilation of the filter segment.

Additional features, advantages, and embodiments of the disclosure may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the disclosure and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the detailed description, serve to explain the principles of the disclosure. No attempt is made to show structural details of the disclosure in more detail than may be necessary for a fundamental understanding of the disclosure and the various ways in which it may be practiced. In the drawings:

FIG. 1A is a schematic drawing depicting a prior art filter design of standard cigarettes.

FIG. 1B is a schematic drawing showing a side view of a cigarette with a new filter design in accordance with the present disclosure.

FIG. 2 is a table showing examples of filter design constructions in accordance with the present disclosure.

FIGS. 3 and 4 are regression charts of the mathematical model for TPM/CO determined in accordance with the present disclosure.

FIG. 5 is a chart showing the tar-to-nicotine relationship of cigarettes with filters design constructions in accordance with the present disclosure.

FIG. 6 is a table showing tar, nicotine, and carbon monoxide delivery of several sample cigarettes with filters constructed according to the present disclosure.

FIGS. 7-9 are descriptive sketches of examples of filters containing heat reflective material in or surrounding the microcapillary and/or filter wrapper.

FIG. 10 is a descriptive sketch of an example of a filter in which fragrances or adsorbent materials are incorporated in the filter design.

FIG. 11 is a descriptive sketch of an example of a filter in which carbon or polymeric adsorbing beads are incorporated in the filter design.

FIG. 12 is a descriptive sketch of an example of a filter in which the microcapillary decreases in diameter in the direction of the mouth piece.

FIGS. 13A and 13B are descriptive sketches of examples of a filter in which the microcapillary can extend further than the filtering tow material to channel smoke delivery into the mouth of a user.

FIG. 14 is a table showing examples in which microcapillary filter segments are combined with other filter segments to control the open pressure drop and alter the perceived draw during smoking

FIG. 15A is a descriptive sketch of an example of a filter in which the microcapillaries are used to segregate the delivered aerosol to the mouth piece of a smoking article.

FIGS. 15B-D show descriptive sketches of examples of the aerosol exit designs of the mouth piece for smoking articles in accordance with the present disclosure.

FIG. 16 is a schematic drawing of a method for making the rod of a cigarette filter in accordance with the present disclosure.

FIG. 17 is table showing the preferred and most preferred ranges for various filter rod attributes constructed in accordance with the present disclosure.

FIG. 18 is a sketch of a typical filter rod and its dimensions in accordance with the present disclosure.

The present disclosure is further described in the detailed description that follows.

DETAILED DESCRIPTION OF THE DISCLOSURE

The disclosure and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings and detailed in the following.

FIG. 1B is a side view of a cigarette 10B with a new filter 14B designed by the present inventors. In this design, the filter 14B is a tubular structure surrounding a non-porous microcapillary tube (or microcapillary) 18 centered axially in the filter 14B. The filter 14B can comprise low density cellulose acetate, for example. Instead of or in addition to cellulose acetate, the filter 14B can also comprise paper or nylon fiber, for example. The microcapillary tube 18 can comprise polycarbonate or other polymeric resins, such as polyethylene, polypropylene, nylon, paper, or cellulose acetate, for example. The filter 14B is designed to reduce the relative amount of CO to the total particulate material (or tar) delivered in mainstream smoke from cigarette 10B, resulting in a TPM to CO ratio greater than or equal to 1.0. Because gas molecules such as CO have an inherently faster rate of diffusion than aerosol particles, CO in mainstream smoke radially diffuses in the cellulose acetate filter faster than the particulate matter. The CO passing through the outer-most circumferential region of the filter 14B is further diluted with air passing through the air ventilation holes 16 located around the outer circumference of the filter 14B. Meanwhile, an ultra-low quantity of particulate smoke is allowed to pass through the central microcapillary 18 relatively unfiltered. It is believed that mass air flow plays an important role in the present filter design, as the delivered smoke at the mouth end 15′ of the cigarette 10B is the sum of the filtered, air-diluted smoke passing through the filter 14B and the unfiltered smoke passing through the microcapillary 18.

The present inventors have found that three factors—the diameter of the microcapillary 18, the density of the filter 14B (also referred to as “tow density”), and the degree of air dilution—can be used to control the TPM/CO ratio. In particular, the present inventors have discovered the following useful relationship:

TPM/CO=0.84−0.14*TT+0.25*TID+0.28*AV+0.36*TID*AV  (1)

where

-   -   TPM is wet total particulate matter in milligrams (mg) per         cigarette;     -   CO is the total amount of carbon monoxide (g) per cigarette;     -   TT is the density of the cellulose acetate filter, which is         controlled by varying the tow type and number of tow strands.         (For example, higher density filters are formed from 42,000         2.6-denier filaments and lower density filters are formed from         39,000 5.0-denier filaments, respectively.)     -   TID is the inner diameter or I.D. of the microcapillary inserted         into the cellulose acetate filter; and     -   AV is cigarette air dilution expressed as a percentage of air         measured between lasered holes in the filter about 13.5 mm from         the mouth end and the non-air-diluted cigarette controls.

This relationship was estimated with a coefficient of determination, adjusted R square, of 0.75.

The above equation (1) can be used to design smoking articles with lower CO delivery at equivalent tar levels of commercially available smoking articles. In addition, because mixing of the unfiltered and the filtered smoke stream occurs in the mouth of the smokers, a fuller impact of the tobacco taste is possible. As such, cigarette 10B with a filter designed according to equation (1) above can provide a fuller tobacco taste at lower overall tar delivery compared to a traditional filtered cigarette 10A.

FIG. 2 is a table 20 showing non-limiting examples of filter design constructions according to the present disclosure. Filter design numbers 1-18 were fabricated based on a full factorial experimental design, wherein the input variables were tow density (measured in denier/filament), microcapillary inner diameter, and percentage of air dilution in the cigarette filter. The filters were 23.85 mm in perimeter and 25 mm in length. The filter material was selected as having either high density (5.0/39K denier/filament) or low density (2.6/42K denier/filament). The cigarettes were smoked in a 32 port Cerulean ASM500 linear smoking machine to characterize their TPM and CO delivery.

The open pressure drop (OPD) of a cigarette is the perceived drop in pressure between a cigarette's mouth piece and ventilation hole. A maximal OPD is typically desirable. In attempting to increase the TMP/CO ratio and maximize the OPD, the present inventors have found that OPD can be described according to the following equation:

OPD=213+19*TT−20*TID−27*AV−(13.5*TID+3.3*AV*TT) where   (2)

-   -   TT is the density of the cellulose acetate filter     -   TID is the inner diameter or I.D. of the microcapillary inserted         into the cellulose acetate filter;     -   AV is cigarette air dilution expressed as a percentage of air         dilution measured between lasered holes in the filter about 13.5         mm from the mouth end and the non-air-diluted cigarette control;         and     -   OPD is the open cigarette pressure drop in millimeters (mm) of         water.         This relationship was estimated with a coefficient of         determination, adjusted R square, of 0.99. In addition, the         closed pressure drop referred to in FIG. 2 is the pressure drop         from the ignitable end of a cigarette to the mouth end measured         using standard physical characterization equipment for         cigarettes.

The table 20 in FIG. 2 illustrates that the TPM/CO ratio can be maximized across multiple tar (TPM) categories. For example, the TPM/CO ratio is about 2 when the TPM concentration is 20.4 mg/cig, 16.3 mg/cig, and 8.9 mg/cig. Therefore, the TPM/CO ratio can be increased for both low tar and high tar cigarettes.

Using equations (1) and (2) above, the present inventors developed the regression charts shown in FIGS. 3 and 4. In FIGS. 3 and 4, the solid marks (triangles, squares, circles) representing the inner diameter of the capillary correspond to the TPM axis on the left, and the open marks (triangles, squares, circles) representing the inner diameter of the capillary correspond to the TPM/CO axis on the right. The filter used to obtain the data shown in FIG. 3 had 2.6 denier/42,000 filaments (low density tow type), whereas the filter used to obtain the data shown in FIG. 4 had 5.0 denier/39,000 filaments (high density tow type). These regression charts provide a way to easily determine percentage of air dilution and inner diameter of the capillary to be used for a desired TPM and TPM/CO ratio combination. For example, if a cigarette designer desires a cigarette with a low density tow type filter, TPM of 13 mg/cigarette, and TPM/CO of 1.8, he/she can choose a 0.5 mm-diameter microcapillary accompanied by 40% air dilution. Thus, the regressions presented in FIGS. 3 and 4 provide ways to design a range of cigarettes with the TPM levels required for different commercial cigarette tar classes.

It should be noted that even though the regressions shown in FIGS. 3 and 4 were created using cigarette filters with microcapillaries with an inner diameter from 0.0 to 1.0 mm, larger inner diameter microcapillaries can be used. For example, the use of 1.5, 2.0, 0, 2.5 and even 3.0 mm microcapillaries is not precluded. Thus, the upper limit for useful inner diameter capillaries is given by the diameter of the smoking device filter segment. Likewise, although FIGS. 3 and 4 present the modeling results for tow density of 2.6/42K and 5.0/39K denier/filament count, respectively, other denier and number of filament combinations are not precluded.

The present inventors have further found that the nicotine level delivered by cigarettes with filters designed to increase the TPM/CO ratio, as described above, is not significantly affected by the use of such filters. The tar-to-nicotine relationship is shown in FIG. 5. This relationship remains relatively consistent, for both a 0.5 mm inner diameter microcapillary and a 1.0 mm inner diameter microcapillary, between cigarettes with filters designed to increase the TPM/CO ratio and control (traditional filter) cigarettes. The smoking conditions used to obtain the data in FIG. 5 were as follows: 2 second puffs; 28 second wait; 35 ml volume displacement in a 32-ports linear smoking machine, Cerulean ASM500; 85 mm cigarette with a commercial tobacco blend; and 25 mm filter length.

FIG. 6 is a table showing tar, nicotine, and carbon monoxide delivery of several sample cigarettes with filters constructed according to the present disclosure. The sample cigarettes had filters with 60% air dilution and ventilation holes located about 13 mm from the mouth end. Cigarette lengths of 80 and 100 mm were used with varying cellulose acetate tow density, microcapillary inner diameter, and microcapillary length. One sample contained a mentholated tobacco column. In addition, some samples were constructed using metallized foil instead of paper for the filter wrapper. It is believed that foil, or other heat reflective or heat absorbent materials, can retain heat in the cellulose acetate tow from the delivered smoke, effectively increasing the diffusion rate of gaseous analytes. In this case, diffusion of CO is increased and subsequently diluted by air passing through the ventilation holes, effectively reducing the level of delivered CO in the smoke. As a result, the TPM/CO ratio is increased.

FIGS. 7-9 are descriptive sketches of examples of filters containing heat reflective material 22 in relation to the microcapillary 18. FIG. 7A shows heat reflective material 22 forming the microcapillary 18, whereas FIG. 7B shows heat reflective material 22 coating the microcapillary 18. In addition to or instead of heat reflective material 22, heat absorbing material (not shown) can also be used. FIGS. 8A and 8B show examples of co-axial arrangements of heat reflective material 22 with respect to the microcapillary 18 and the filter segment 14B. In FIG. 8A, the heat reflective material 22 forms the microcapillary 18 and forms a wrapper 24 around the filter segment 14B. In FIG. 8B, the heat reflective material 22 coats the microcapillary 18 and forms a wrapper 24 around the filter segment 14B. FIG. 9 shows heat reflective material 22 forming the filter wrapper 24 only. Based on principles of thermophoresis, the relative proportion of TPM/CO in delivered tobacco smoke can be further controlled by minimizing the differential temperature between the microcapillary 18 and the smoke passing through the filter segment 14B. Thus, it is believed that designing a microcapillary to control smoke flow and temperature will allow for an increased TPM/CO ratio.

In addition, because the filter segments 14B illustrated in FIGS. 7-9 form two discrete zones, these zones could be used to carry independently encapsulated fragrances, highly adsorbent materials (i.e., tobacco concentrates, defibrillated fibers, microfibers, etc.) and/or functionalized polymeric beads or carbon material. For example, as shown in FIG. 10, fragrances or adsorbent materials can be used to design flavored cigarettes or potentially reduced exposure product (PREP) cigarettes or combinations thereof. Further, as shown in FIG. 11, carbon beads in the filter can be used to further scrub out volatile materials such as CO. Moreover, another benefit in the case of carbon/adsorbent beads is an improvement in taste and customer acceptance, since a portion of the smoke stream does not lose desirable fragrance and taste components that would be otherwise adsorbed.

FIG. 12 shows an example of another embodiment of filter construction in which the microcapillary 18A decreases in diameter in the direction of the mouth end 15′. The decreasing diameter of microcapillary 18A can allow control of the delivered tar due to a greater pressure drop difference between the microcapillary and the surrounding material, which causes less smoke to pass through the microcapillary.

A mouth end segment 26 can be made of plastic or other non-absorbent material, as shown in FIG. 13A to conceal the microcapillary 18 or alter its appearance. The mouth end segment 26 can further be fabricated to include design features to augment the smoking experience, such as tapering the diameter of the microcapillary 18 in the mouth end segment 26 to increase the pressure drop and further organoleptic enhancement. Furthermore, mouth piece embodiments include design features that disperse the delivered smoke in the mouth of the user. FIG. 13B illustrates a fluted mouth end segment 26 with microcapillary supports 28 that allows the smoke to disperse radially into the mouth when smoke is inhaled.

The presently disclosed filter designs can include a plurality of filter segments to further modify the delivered smoke characteristics and alter the appearance of the filter mouth end. FIG. 14 is a table 30 showing non-limiting embodiments in which filter segments with inserted microcapillaries are combined with additional filter segments (e.g., non-absorbing inserts or cellulose acetate inserts) at the mouth end of the cigarette to control the open pressure drop and alter the perceived draw while maintaining a desirable tar/CO ratio.

Mouth end segments useful to the practice of this invention can be built in numerous configurations and designs. For example, mouth end segments can be built with cellulose acetate tow to conceal single or multiple microcapillaries. Mouth end segments can be used with e-cigarettes in addition to traditional tobacco cigarettes. Mouth end segments can also be built according to designs that functionalize the aerosol stream by proportionally mixing aerosol of different compositions which originate from single or multiple capillaries, as shown in FIG. 15A. FIG. 15A shows an exemplary design for microcapillary 18B that is conically-shaped near the mouth end 15′, coupled with a mouth segment 26B designed to produce two different aerosol streams, 32 and 34, which are kept separated until mixing in the user's mouth. In this example, aerosol stream 32 arises from filtered and air-diluted smoke from filter 14B, while aerosol stream 34 arises from unfiltered smoke passing through the microcapillary 18B.

Additionally, mouth end segments can also be built according to designs that affect the smoking experience by controlling the aerosol direction and/or velocity exiting the mouth end, as shown in FIGS. 15B-15D. FIGS. 15B-15D illustrate various exemplary shapes and combinations of aerosol exit ports (or inlets) 36 in the mouth piece. In FIG. 15B, the aerosol exits ports 36 are annular rings. In FIG. 15C, there are annular and perforated aerosol exit ports 36. In FIG. 15D, there are annular and slatted aerosol exit ports 36. Finally, mouth end segments can be built according to any combination of the methods discussed above.

FIGS. 16-18 relate to a method for making the rod of a cigarette filter 14B in accordance with the present disclosure. FIG. 16 is a schematic drawing of the method of fabrication. The present method comprises incorporating plastic or other microcapillary tubing 18 into cellulose acetate filter rods using a conventional filter maker. This can be accomplished by inserting the microcapillary 18 onto the path of a moving tow band. Cellulose filament bundles can be passed through a plug maker garniture to spread the tow filaments using equipment known in the cigarette filter making art. Then the tow and the microcapillary can be wrapped together with paper. The microcapillary can be added from a spool into the garniture after the addition of a plasticizer and final conversion into filter rods. However, the microcapillary can also be added prior to addition of the plasticizer. In addition, a tow density enhancer or plasticizer, such as triacetin, polyvinyl acetate, or polyvinyl alcohol, can be sprayed onto the moving tow to control tow density. FIG. 17 is table showing the preferred and most preferred ranges for various filter rod attributes constructed according to the method, and FIG. 18 shows a typical filter rod containing the microcapillary and surrounding filtration material and its dimensions. 

What is claimed is:
 1. A smoking article comprising a tobacco column comprising a proximal end and a distal ignitable end, the tobacco column configured to generate products of combustion comprising at least one of tar and carbon monoxide; and a filter segment, comprising a proximal mouth end and a distal end coupled to the tobacco column, the filter segment further comprising a tubular filter structure surrounding a non-porous microcapillary tube, the microcapillary tube centered axially within the tubular filter structure; wherein smoke inhaled by a user at the proximal mouth end of the filter segment comprises a ratio of tar to carbon monoxide that is greater than or equal to 1.0.
 2. The smoking article of claim 1, wherein the filter segment further comprises at least one of the following: cellulose acetate, paper, and nylon fiber.
 3. The smoking article of claim 1, wherein the microcapillary tube comprises at least one of the following: a polycarbonate or other polymeric resins, including polyethylene, polypropylene, nylon, paper, and cellulose acetate.
 4. The smoking article of claim 1, wherein the smoke inhaled by the user further comprises a reduced amount of carbon monoxide as compared to smoke filtered by a solid filter of a standard cigarette.
 5. The smoking article of claim 1, wherein the smoke inhaled by the user further comprises a reduced amount of carbon dioxide and a reduced amount of tar as compared to smoke filtered by a solid filter of a standard cigarette.
 6. The smoking article of claim 1, wherein the ratio of tar to carbon monoxide is a function of at least one of the following: a diameter of the microcapillary tube, a density of the filter segment, and a degree of air ventilation of the filter segment.
 7. The smoking article of claim 1, wherein the smoke inhaled by the user further comprises a consistent ratio of tar to nicotine as compared to smoke filtered by a solid filter of a standard cigarette.
 8. The smoking article of claim 1, wherein the filter segment further comprises a heat reflective or heat absorbent material that coats or forms at least one of the microcapillary tube or the tubular filter structure.
 9. The smoking article of claim 1, wherein the filter segment further comprises at least one of the following: a fragrance, an encapsulated fragrance, polymeric beads, or carbon beads.
 10. The smoking article of claim 1, wherein a diameter of the microcapillary tube varies within the tubular filter structure.
 11. The smoking article of claim 1, further comprising a mouth piece coupled to the proximal mouth end of the filter segment.
 12. The smoking article of claim 11, wherein the mouth piece is configured to disperse smoke delivered in the user's mouth.
 13. The smoking article of claim 11, wherein the mouth piece is configured to conceal the microcapillary tube.
 14. The smoking article of claim 11, wherein the mouth piece comprises a pattern of inlets configured to control a direction or a velocity of aerosol exiting the mouth piece.
 15. A filter segment for use in a smoking article, the filter segment comprising a tubular filter structure surrounding a non-porous microcapillary tube, the microcapillary tube centered axially within the tubular filter structure; wherein smoke inhaled by a user of the smoking article comprises a ratio of tar to carbon monoxide that is greater than or equal to 1.0.
 16. The filter segment of claim 15, further comprising at least one of the following: cellulose acetate, paper, and nylon fiber.
 17. The filter segment of claim 15, wherein the microcapillary tube comprises at least one of the following: a polycarbonate or other polymeric resins, including polyethylene, polypropylene, nylon, paper, and cellulose acetate.
 18. The filter segment of claim 15, wherein the smoke inhaled by the user further comprises a reduced amount of carbon monoxide as compared to smoke filtered by a solid filter of a standard cigarette.
 19. The filter segment of claim 15, wherein the smoke inhaled by the user further comprises a reduced amount of carbon dioxide and a reduced amount of tar as compared to smoke filtered by a solid filter of a standard cigarette.
 20. The filter segment of claim 15, wherein the ratio of tar to carbon monoxide is a function of at least one of the following: a diameter of the microcapillary tube, a density of the filter segment, and a degree of air ventilation of the filter segment.
 21. The filter segment of claim 15, wherein the smoke inhaled by the user further comprises a consistent ratio of tar to nicotine as compared to smoke filtered by a solid filter of a standard cigarette.
 22. The filter segment of claim 15, further comprising a heat reflective or heat absorbent material that coats or forms at least one of the microcapillary tube or the tubular filter structure.
 23. The filter segment of claim 15, further comprising at least one of the following: a fragrance, an encapsulated fragrance, polymeric beads, or carbon beads.
 24. The filter segment of claim 15, wherein a diameter of the microcapillary tube varies within the tubular filter structure.
 25. The filter segment of claim 15, further comprising a mouth piece coupled to the tubular filter structure.
 26. The filter segment of claim 25, wherein the mouth piece is configured to disperse smoke delivered in the user's mouth.
 27. The filter segment of claim 25, wherein the mouth piece is configured to conceal the microcapillary tube.
 28. The filter segment of claim 25, wherein the mouth piece comprises a pattern of inlets configured to control a direction or a velocity of aerosol exiting the mouth piece.
 29. A method for reducing an amount of carbon monoxide in mainstream cigarette smoke, the method comprising: inserting a non-porous microcapillary tube axially into a filter segment of a cigarette; and controlling at least one of a diameter of the microcapillary tube, a density of the filter segment, and a degree of air ventilation of the filter segment.
 30. The method of claim 29, wherein smoke inhaled by a user of the cigarette comprises a ratio of tar to carbon monoxide that is greater than or equal to 1.0. 